Content addressable storage system configured for efficient storage of count-key-data tracks

ABSTRACT

A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage system is configured by the storage controller to receive a plurality of data records in a count-key-data format, to separate count and key portions of the data records from remaining portions of the data records, to store the count and key portions of the data records in at least one designated page of a set of pages of a logical storage volume of the storage system, and to store the remaining portions of the data records in one or more other pages of the set of pages of the logical storage volume of the storage system. The designated page of the set of pages of the logical storage volume may comprise a first page of the set of pages, and the one or more other pages of the set of pages may comprise respective ones of a sequence of consecutive pages following the first page.

FIELD

The field relates generally to information processing systems, and moreparticularly to storage in information processing systems.

BACKGROUND

Various types of content addressable storage systems are known. Somecontent addressable storage systems allow data pages of one or morelogical storage volumes to be accessed using content-based signaturesthat are computed from content of respective ones of the data pages.Such content addressable storage system arrangements facilitateimplementation of deduplication and compression. For example, thestorage system need only maintain a single copy of a given data pageeven though that same data page may be part of multiple logical storagevolumes. Although these and other content addressable storage systemstypically provide a high level of storage efficiency throughdeduplication and compression, the storage efficiency may besignificantly degraded when storing data in certain data formats,thereby undermining overall system performance. For example, storageefficiency can be degraded when storing data in a count-key-data formatof the type commonly used by mainframe storage systems that do not havecontent addressable storage functionality.

SUMMARY

Illustrative embodiments provide content addressable storage systemsthat are configured for efficient storage of count-key-data tracks ofthe type commonly utilized in a mainframe storage system that does nothave content addressable storage functionality. For example, suchembodiments can provide a high level of storage efficiency throughdeduplication and compression even when storing count-key-data tracks.The storage efficiency of the content addressable storage system istherefore not degraded in any significant way when storing data intypical mainframe storage system formats.

These embodiments illustratively include a clustered implementation of acontent addressable storage system having a distributed storagecontroller. Similar advantages can be provided in other types of storagesystems.

In one embodiment, an apparatus comprises a storage system comprising aplurality of storage devices and a storage controller. The storagesystem is configured by the storage controller to receive a plurality ofdata records in a count-key-data format, to separate count and keyportions of the data records from remaining portions of the datarecords, to store the count and key portions of the data records in atleast one designated page of a set of pages of a logical storage volumeof the storage system, and to store the remaining portions of the datarecords in one or more other pages of the set of pages of the logicalstorage volume of the storage system. The designated page of the set ofpages of the logical storage volume may comprise a first page of the setof pages, and the one or more other pages of the set of pages maycomprise respective ones of a sequence of consecutive pages followingthe first page.

The data records are illustratively part of a particular trackcomprising multiple data records in the count-key-data format, althoughin other embodiments the data records may be part of multiple trackseach comprising multiple data records in the count-key-data format. Thecount portion for a given one of the data records comprises a countfield indicating a length of the given data record, and the key portionfor the given data record comprises a key field including keyinformation of that data record. The remaining portion for the givendata record comprises user data of the given data record.

In some embodiments, storing the count and key portions of the datarecords in at least one designated page of a set of pages of a logicalstorage volume of the storage system comprises storing the count and keyportions for a given one of the records in the designated page inassociation with a pointer to a location of the remaining portion of thegiven one of the records in the one or more other pages of the set ofpages.

The designated page may therefore comprise a plurality of entries forcount and key portions of respective ones of the data records, with eachof the entries of the designated page comprising count and key portionsfor a given one of the data records and a pointer to a location of theremaining portion of the given one of the records in the one or moreother pages of the set of pages.

In some embodiments, the storage system may be configured to perform adeduplication operation on the one or more other pages of the set ofpages of the logical storage volume but not on the designated page ofthe set of pages.

Additionally or alternatively, the storage system may be configured toperform a compression operation on the one or more other pages of theset of pages of the logical storage volume but not on the designatedpage of the set of pages.

The storage system in some embodiments comprises a content addressablestorage system implemented utilizing non-volatile memory storagedevices, such as flash-based storage devices. For example, the storagedevices of the storage system in such embodiments can be configured tocollectively provide an all-flash storage array. Numerous other storagesystem arrangements are possible in other embodiments.

These and other illustrative embodiments include, without limitation,apparatus, systems, methods and processor-readable storage media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an information processing system comprisinga content addressable storage system configured for efficient storage ofcount-key-data tracks in an illustrative embodiment.

FIG. 2 is a flow diagram of a process for efficient storage ofcount-key-data tracks in a content addressable storage system in anillustrative embodiment.

FIG. 3 shows an example track of data records in a count-key-data formatin an illustrative embodiment.

FIG. 4 shows an example of a manner in which the data records of FIG. 3are stored utilizing a designated page for count and key portions andadditional pages for remaining portions in an illustrative embodiment.

FIG. 5 shows a more detailed view of the page of FIG. 4 containing countand key portions of the data records in association with respectivepointers to remaining user data portions of those data records in anillustrative embodiment.

FIGS. 6 and 7 show examples of processing platforms that may be utilizedto implement at least a portion of an information processing system inillustrative embodiments.

DETAILED DESCRIPTION

Illustrative embodiments will be described herein with reference toexemplary information processing systems and associated computers,servers, storage devices and other processing devices. It is to beappreciated, however, that these and other embodiments are notrestricted to the particular illustrative system and deviceconfigurations shown. Accordingly, the term “information processingsystem” as used herein is intended to be broadly construed, so as toencompass, for example, processing systems comprising cloud computingand storage systems, as well as other types of processing systemscomprising various combinations of physical and virtual processingresources. An information processing system may therefore comprise, forexample, at least one data center or other cloud-based system thatincludes one or more clouds hosting multiple tenants that share cloudresources. Numerous different types of enterprise computing and storagesystems are also encompassed by the term “information processing system”as that term is broadly used herein.

FIG. 1 shows an information processing system 100 configured inaccordance with an illustrative embodiment. The information processingsystem 100 comprises a computer system 101 that includes host devices102-1, 102-2, . . . 102-N. The host devices 102 communicate over anetwork 104 with a content addressable storage system 105. The contentaddressable storage system 105 is an example of what is more generallyreferred to herein as a “storage system,” and it is to be appreciatedthat a wide variety of other types of storage systems can be used inother embodiments.

The host devices 102 and content addressable storage system 105illustratively comprise respective processing devices of one or moreprocessing platforms. For example, the host devices 102 and the contentaddressable storage system 105 can each comprise one or more processingdevices each having a processor and a memory, possibly implementingvirtual machines and/or containers, although numerous otherconfigurations are possible.

The host devices 102 and content addressable storage system 105 may bepart of an enterprise computing and storage system, a cloud-based systemor another type of system. For example, the host devices 102 and thecontent addressable storage system 105 can be part of cloudinfrastructure such as an Amazon Web Services (AWS) system. Otherexamples of cloud-based systems that can be used to provide one or moreof host devices 102 and content addressable storage system 105 includeGoogle Cloud Platform (GCP) and Microsoft Azure.

The host devices 102 are configured to write data to and read data fromthe content addressable storage system 105. The host devices 102 and thecontent addressable storage system 105 may be implemented on a commonprocessing platform, or on separate processing platforms. A wide varietyof other types of host devices can be used in other embodiments.

The host devices 102 in some embodiments illustratively provide computeservices such as execution of one or more applications on behalf of eachof one or more users associated with respective ones of the host devices102.

The term “user” herein is intended to be broadly construed so as toencompass numerous arrangements of human, hardware, software or firmwareentities, as well as combinations of such entities. Compute and/orstorage services may be provided for users under a platform-as-a-service(PaaS) model, although it is to be appreciated that numerous other cloudinfrastructure arrangements could be used. Also, illustrativeembodiments can be implemented outside of the cloud infrastructurecontext, as in the case of a stand-alone computing and storage systemimplemented within a given enterprise.

The network 104 is assumed to comprise a portion of a global computernetwork such as the Internet, although other types of networks can bepart of the network 104, including a wide area network (WAN), a localarea network (LAN), a satellite network, a telephone or cable network, acellular network, a wireless network such as a WiFi or WiMAX network, orvarious portions or combinations of these and other types of networks.The network 104 in some embodiments therefore comprises combinations ofmultiple different types of networks each comprising processing devicesconfigured to communicate using Internet Protocol (IP) or othercommunication protocols.

As a more particular example, some embodiments may utilize one or morehigh-speed local networks in which associated processing devicescommunicate with one another utilizing Peripheral Component Interconnectexpress (PCIe) cards of those devices, and networking protocols such asInfiniBand, Gigabit Ethernet or Fibre Channel. Numerous alternativenetworking arrangements are possible in a given embodiment, as will beappreciated by those skilled in the art.

The content addressable storage system 105 is accessible to the hostdevices 102 over the network 104. The content addressable storage system105 comprises a plurality of storage devices 106 and an associatedstorage controller 108. The storage devices 106 illustratively storemetadata pages 110 and user data pages 112. The user data pages 112 insome embodiments are organized into sets of logical units (LUNs) eachaccessible to one or more of the host devices 102. The LUNs may beviewed as examples of what are also referred to herein as logicalstorage volumes of the content addressable storage system 105.

The storage devices 106 illustratively comprise solid state drives(SSDs). Such SSDs are implemented using non-volatile memory (NVM)devices such as flash memory. Other types of NVM devices that can beused to implement at least a portion of the storage devices 106 includenon-volatile random access memory (NVRAM), phase-change RAM (PC-RAM) andmagnetic RAM (MRAM). These and various combinations of multipledifferent types of NVM devices may also be used.

However, it is to be appreciated that other types of storage devices canbe used in other embodiments. For example, a given storage system as theterm is broadly used herein can include a combination of different typesof storage devices, as in the case of a multi-tier storage systemcomprising a flash-based fast tier and a disk-based capacity tier. Insuch an embodiment, each of the fast tier and the capacity tier of themulti-tier storage system comprises a plurality of storage devices withdifferent types of storage devices being used in different ones of thestorage tiers. For example, the fast tier may comprise flash driveswhile the capacity tier comprises hard disk drives. The particularstorage devices used in a given storage tier may be varied in otherembodiments, and multiple distinct storage device types may be usedwithin a single storage tier. The term “storage device” as used hereinis intended to be broadly construed, so as to encompass, for example,flash drives, solid state drives, hard disk drives, hybrid drives orother types of storage devices.

In some embodiments, the content addressable storage system 105illustratively comprises a scale-out all-flash content addressablestorage array such as an XtremIO™ storage array from Dell EMC ofHopkinton, Mass. For example, the content addressable storage system 105can comprise an otherwise conventional XtremIO™ storage array or othertype of content addressable storage system that is suitably modified toincorporate efficient storage of count-key-data tracks as disclosedherein. Other types of storage arrays, including by way of example VNX®and Symmetrix VMAX® storage arrays also from Dell EMC, can be used toimplement content addressable storage system 105 in other embodiments.

The term “storage system” as used herein is therefore intended to bebroadly construed, and should not be viewed as being limited to contentaddressable storage systems or flash-based storage systems. A givenstorage system as the term is broadly used herein can comprise, forexample, network-attached storage (NAS), storage area networks (SANs),direct-attached storage (DAS) and distributed DAS, as well ascombinations of these and other storage types, includingsoftware-defined storage.

Other particular types of storage products that can be used inimplementing content addressable storage system 105 in illustrativeembodiments include all-flash and hybrid flash storage arrays such asUnity™, software-defined storage products such as ScaleIO™ and ViPR®,cloud storage products such as Elastic Cloud Storage (ECS), object-basedstorage products such as Atmos®, and scale-out NAS clusters comprisingIsilon® platform nodes and associated accelerators, all from Dell EMC.Combinations of multiple ones of these and other storage products canalso be used in implementing a given storage system in an illustrativeembodiment.

The content addressable storage system 105 in the FIG. 1 embodiment isimplemented as at least a portion of a clustered storage system andincludes a plurality of storage nodes 115 each comprising acorresponding subset of the storage devices 106. Other clustered storagesystem arrangements comprising multiple storage nodes can be used inother embodiments. A given clustered storage system may include not onlystorage nodes 115 but also additional storage nodes 120 coupled tonetwork 104. Alternatively, such additional storage nodes 120 may bepart of another clustered storage system of the system 100. Each of thestorage nodes 115 of the content addressable storage system 105 isassumed to be implemented using at least one processing devicecomprising a processor coupled to a memory.

The storage controller 108 of the content addressable storage system 105in the present embodiment is configured to control the implementation offunctionality for efficient storage of count-key-data tracks asdisclosed herein. The storage controller 108 is assumed to comprise atype of “processing device” as that term is broadly used herein, andmore particularly comprises at least one processor coupled to a memory.The content addressable storage system 105 under the control of thestorage controller 108 is operative to receive a plurality of datarecords in a count-key-data format, to separate count and key portionsof the data records from remaining portions of the data records, tostore the count and key portions of the data records in at least onedesignated page of a set of pages of a logical storage volume of thecontent addressable storage system 105, and to store the remainingportions of the data records in one or more other pages of the set ofpages of the logical storage volume of the content addressable storagesystem 105. The set of pages illustratively comprises at least a portionof at least one LUN comprising multiple ones of the user data pages 112.

For example, in some embodiments, the designated page of the set ofpages of the logical storage volume comprises a first page of the set ofpages, and the one or more other pages of the set of pages compriserespective ones of a sequence of consecutive pages following the firstpage. A more detailed example of an arrangement of this type will bedescribed below in conjunction with FIGS. 3, 4 and 5.

The data records are illustratively part of a particular trackcomprising multiple data records in the count-key-data format. Forexample, the count portion for a given one of the data recordsillustratively comprises a count field indicating a length of the givendata record, the key portion for the given one of the data recordscomprises a key field including key information of the given datarecord, and the remaining portion for the given one of the data recordscomprises user data of the given data record. Other types ofcount-key-data formats may be used in other embodiments. The term“count-key-data” as used herein is intended to be broadly construed, andshould not be construed as limited to the particular arrangements usedin any of the format examples described herein. Also, terms such as“track” and “data record” as used herein are similarly intended to bebroadly construed.

For example, a “track” may refer to a designated portion of a storagedevice “cylinder” that contains a plurality of tracks, with each trackcomprising a plurality of data records each having count, key and datafields in accordance with the count-key-data format. Other track anddata record configurations can be used in other embodiments.

In some embodiments, storing the count and key portions of the datarecords in at least one designated page of a set of pages of a logicalstorage volume of the content addressable storage system 105 comprisesstoring the count and key portions for a given one of the records in thedesignated page in association with a pointer to a location of theremaining portion of the given one of the records in the one or moreother pages of the set of pages.

Accordingly, the designated page illustratively comprises a plurality ofentries for count and key portions of respective ones of the datarecords with each of the entries of the designated page comprising countand key portions for a given one of the data records and a pointer to alocation of the remaining portion of the given one of the records in theone or more other pages of the set of pages.

The content addressable storage system 105 under the control of thestorage controller 108 can be configured to perform deduplication and/orcompression operations on at least a portion of the set of pages,possibly bypassing the designated page in which the count and keyportions of the data records are stored as the designated page isunlikely to be significantly reducible via deduplication and/orcompression.

Thus, in some embodiments, the content addressable storage system 105 isconfigured to perform a deduplication operation on the one or more otherpages of the set of pages of the logical storage volume but not on thedesignated page of the set of pages, and/or to perform a compressionoperation on the one or more other pages of the set of pages of thelogical storage volume but not on the designated page of the set ofpages. Alternatively, deduplication and/or compression operations can beperformed on the full set of pages, possibly in combination with othersets of pages, even though the designated page of the full set of pagesis unlikely to be significantly reducible via deduplication and/orcompression.

The storage controller 108 in this embodiment is implemented in adistributed manner so as to comprise a plurality of distributed storagecontroller components implemented on respective ones of the storagenodes 115. The storage controller 108 is therefore an example of what ismore generally referred to herein as a “distributed storage controller.”Accordingly, in subsequent description herein, the storage controller108 is more particularly referred to as a distributed storagecontroller. Other types of potentially non-distributed storagecontrollers can be used in other embodiments.

Each of the storage nodes 115 in this embodiment further comprises a setof processing modules configured to communicate over one or morenetworks with corresponding sets of processing modules on other ones ofthe storage nodes 115. The sets of processing modules of the storagenodes 115 collectively comprise at least a portion of the distributedstorage controller 108 of the content addressable storage system 105.

The modules of the distributed storage controller 108 in the presentembodiment more particularly comprise different sets of processingmodules implemented on each of the storage nodes 115. The set ofprocessing modules of each of the storage nodes 115 comprises at least acontrol module 108C, a data module 108D and a routing module 108R. Thedistributed storage controller 108 further comprises one or moremanagement (“MGMT”) modules 108M. For example, only a single one of thestorage nodes 115 may include a management module 108M. It is alsopossible that management modules 108M may be implemented on each of atleast a subset of the storage nodes 115.

Each of the storage nodes 115 of the content addressable storage system105 therefore comprises a set of processing modules configured tocommunicate over one or more networks with corresponding sets ofprocessing modules on other ones of the storage nodes. A given such setof processing modules implemented on a particular storage nodeillustratively includes at least one control module 108C, at least onedata module 108D and at least one routing module 108R, and possibly amanagement module 108M. These sets of processing modules of the storagenodes collectively comprise at least a portion of the distributedstorage controller 108.

Communication links may be established between the various processingmodules of the distributed storage controller 108 using well-knowncommunication protocols such as IP and Transmission Control Protocol(TCP). For example, respective sets of IP links used in data transferand corresponding messaging could be associated with respectivedifferent ones of the routing modules 108R.

The storage devices 106 are configured to store metadata pages 110 anduser data pages 112, and may also store additional information notexplicitly shown such as checkpoints and write journals. The metadatapages 110 and the user data pages 112 are illustratively stored inrespective designated metadata and user data areas of the storagedevices 106. Accordingly, metadata pages 110 and user data pages 112 maybe viewed as corresponding to respective designated metadata and userdata areas of the storage devices 106.

The term “page” as used herein is intended to be broadly construed so asto encompass any of a wide variety of different types of blocks that maybe utilized in a block storage device of a storage system. Such storagesystems are not limited to content addressable storage systems of thetype disclosed in some embodiments herein, but are more generallyapplicable to any storage system that includes one or more block storagedevices. Different native page sizes are generally utilized in differentstorage systems of different types. For example, XtremIO™ X1 storagearrays utilize a native page size of 8 KB, while XtremIO™ X2 storagearrays utilize a native page size of 16 KB. Larger native page sizes of64 KB and 128 KB are utilized in VMAX® V2 and VMAX® V3 storage arrays,respectively. The native page size generally refers to a typical pagesize at which the storage system ordinarily operates, although it ispossible that some storage systems may support multiple distinct pagesizes as a configurable parameter of the system. Each such page size ofa given storage system may be considered a “native page size” of thestorage system as that term is broadly used herein.

A given “page” as the term is broadly used herein should therefore notbe viewed as being limited to any particular range of fixed sizes. Insome embodiments, a page size of 8 KB is used, but this is by way ofexample only and can be varied in other embodiments. For example, pagesizes of 4 KB, 16 KB or other values can be used. Accordingly,illustrative embodiments can utilize any of a wide variety ofalternative paging arrangements for organizing the metadata pages 110and the user data pages 112.

The user data pages 112 are part of a plurality of LUNs configured tostore files, blocks, objects or other arrangements of data, each alsogenerally referred to herein as a “data item,” on behalf of usersassociated with host devices 102. Each such LUN may comprise particularones of the above-noted pages of the user data area. The user datastored in the user data pages 112 can include any type of user data thatmay be utilized in the system 100. The term “user data” herein istherefore also intended to be broadly construed.

The content addressable storage system 105 is configured to generatehash metadata providing a mapping between content-based digests ofrespective ones of the user data pages 112 and corresponding physicallocations of those pages in the user data area. Content-based digestsgenerated using hash functions are also referred to herein as “hashdigests.” Such hash digests or other types of content-based digests areexamples of what are more generally referred to herein as “content-basedsignatures” of the respective user data pages 112. The hash metadatagenerated by the content addressable storage system 105 isillustratively stored as metadata pages 110 in the metadata area. Thegeneration and storage of the hash metadata is assumed to be performedunder the control of the distributed storage controller 108.

Each of the metadata pages 110 characterizes a plurality of the userdata pages 112. For example, a given set of user data pages representinga portion of the user data pages 112 illustratively comprises aplurality of user data pages denoted User Data Page 1, User Data Page 2,. . . User Data Page n.

Each of the user data pages 112 in this example is characterized by aLUN identifier, an offset and a content-based signature. Thecontent-based signature is generated as a hash function of content ofthe corresponding user data page. Illustrative hash functions that maybe used to generate the content-based signature include the above-notedSHA1 hash function, or other secure hashing algorithms known to thoseskilled in the art. The content-based signature is utilized to determinethe location of the corresponding user data page within the user dataarea of the storage devices 106.

Each of the metadata pages 110 in the present embodiment is assumed tohave a signature that is not content-based. For example, the metadatapage signatures may be generated using hash functions or other signaturegeneration algorithms that do not utilize content of the metadata pagesas input to the signature generation algorithm. Also, each of themetadata pages is assumed to characterize a different set of the userdata pages.

A given set of metadata pages representing a portion of the metadatapages 110 in an illustrative embodiment comprises metadata pages denotedMetadata Page 1, Metadata Page 2, . . . Metadata Page m, havingrespective signatures denoted Signature 1, Signature 2, . . . Signaturem. Each such metadata page characterizes a different set of n user datapages. For example, the characterizing information in each metadata pagecan include the LUN identifiers, offsets and content-based signaturesfor each of the n user data pages that are characterized by thatmetadata page. It is to be appreciated, however, that the user data andmetadata page configurations described above are examples only, andnumerous alternative user data and metadata page configurations can beused in other embodiments.

Ownership of a user data logical address space within the contentaddressable storage system 105 is illustratively distributed among thecontrol modules 108C.

The count-key-data track storage functionality in this embodiment isassumed to be distributed across multiple distributed processingmodules, including at least a subset of the processing modules 108C,108D, 108R and 108M of the distributed storage controller 108.

For example, the management module 108M of the distributed storagecontroller 108 may include count-key-data track storage control logicthat engages or otherwise interacts with corresponding control logicinstances in all of the control modules 108C and routing modules 108R inorder to implement a count-key-data track storage process.

In some embodiments, the content addressable storage system 105comprises an XtremIO™ storage array suitably modified to incorporatetechniques for efficient storage of count-key-data tracks as disclosedherein.

In arrangements of this type, the control modules 108C, data modules108D and routing modules 108R of the distributed storage controller 108illustratively comprise respective C-modules, D-modules and R-modules ofthe XtremIO™ storage array. The one or more management modules 108M ofthe distributed storage controller 108 in such arrangementsillustratively comprise a system-wide management module (“SYM module”)of the XtremIO™ storage array, although other types and arrangements ofsystem-wide management modules can be used in other embodiments.Accordingly, count-key-data track storage functionality in someembodiments is implemented under the control of at least one system-widemanagement module of the distributed storage controller 108, utilizingthe C-modules, D-modules and R-modules of the XtremIO™ storage array.

In the above-described XtremIO™ storage array example, each user datapage has a fixed size such as 8 KB and its content-based signature is a20-byte signature generated using an SHA1 hash function. Also, each pagehas a LUN identifier and an offset, and so is characterized by <lun_id,offset, signature>.

The content-based signature in the present example comprises acontent-based digest of the corresponding data page. Such acontent-based digest is more particularly referred to as a “hash digest”of the corresponding data page, as the content-based signature isillustratively generated by applying a hash function such as SHA1 to thecontent of that data page. The full hash digest of a given data page isgiven by the above-noted 20-byte signature. The hash digest may berepresented by a corresponding “hash handle,” which in some cases maycomprise a particular portion of the hash digest. The hash handleillustratively maps on a one-to-one basis to the corresponding full hashdigest within a designated cluster boundary or other specified storageresource boundary of a given storage system. In arrangements of thistype, the hash handle provides a lightweight mechanism for uniquelyidentifying the corresponding full hash digest and its associated datapage within the specified storage resource boundary. The hash digest andhash handle are both considered examples of “content-based signatures”as that term is broadly used herein.

Examples of techniques for generating and processing hash handles forrespective hash digests of respective data pages are disclosed in U.S.Pat. No. 9,208,162, entitled “Generating a Short Hash Handle,” and U.S.Pat. No. 9,286,003, entitled “Method and Apparatus for Creating a ShortHash Handle Highly Correlated with a Globally-Unique Hash Signature,”both of which are incorporated by reference herein.

As mentioned previously, storage controller components in an XtremIO™storage array illustratively include C-module, D-module and R-modulecomponents. For example, separate instances of such components can beassociated with each of a plurality of storage nodes in a clusteredstorage system implementation.

The distributed storage controller 108 in this example is configured togroup consecutive pages into page groups, to arrange the page groupsinto slices, and to assign the slices to different ones of theC-modules. For example, if there are 1024 slices distributed evenlyacross the C-modules, and there are a total of 16 C-modules in a givenimplementation, each of the C-modules “owns” 1024/16=64 slices. In sucharrangements, different ones of the slices are assigned to differentones of the control modules 108C such that control of the slices withinthe distributed storage controller 108 is substantially evenlydistributed over the control modules 108C of the distributed storagecontroller 108.

The D-module allows a user to locate a given user data page based on itssignature. Each metadata page also has a size of 8 KB and includesmultiple instances of the <lun_id, offset, signature> for respectiveones of a plurality of the user data pages. Such metadata pages areillustratively generated by the C-module but are accessed using theD-module based on a metadata page signature.

The metadata page signature in this embodiment is a 20-byte signaturebut is not based on the content of the metadata page. Instead, themetadata page signature is generated based on an 8-byte metadata pageidentifier that is a function of the LUN identifier and offsetinformation of that metadata page.

If a user wants to read a user data page having a particular LUNidentifier and offset, the corresponding metadata page identifier isfirst determined, then the metadata page signature is computed for theidentified metadata page, and then the metadata page is read using thecomputed signature. In this embodiment, the metadata page signature ismore particularly computed using a signature generation algorithm thatgenerates the signature to include a hash of the 8-byte metadata pageidentifier, one or more ASCII codes for particular predeterminedcharacters, as well as possible additional fields. The last bit of themetadata page signature may always be set to a particular logic value soas to distinguish it from the user data page signature in which the lastbit may always be set to the opposite logic value.

The metadata page signature is used to retrieve the metadata page viathe D-module. This metadata page will include the <lun_id, offset,signature> for the user data page if the user page exists. The signatureof the user data page is then used to retrieve that user data page, alsovia the D-module.

Write requests processed in the content addressable storage system 105each illustratively comprise one or more IO operations directing that atleast one data item of the content addressable storage system 105 bewritten to in a particular manner. A given write request isillustratively received in the content addressable storage system 105from a host device, illustratively one of the host devices 102. In someembodiments, a write request is received in the distributed storagecontroller 108 of the content addressable storage system 105, anddirected from one processing module to another processing module of thedistributed storage controller 108. For example, a received writerequest may be directed from a routing module 108R of the distributedstorage controller 108 to a particular control module 108C of thedistributed storage controller 108. Other arrangements for receiving andprocessing write requests from one or more host devices can be used.

The term “write request” as used herein is intended to be broadlyconstrued, so as to encompass one or more IO operations directing thatat least one data item of a storage system be written to in a particularmanner. A given write request is illustratively received in a storagesystem from a host device.

In the XtremIO™ context, the C-modules, D-modules and R-modules of thestorage nodes 115 communicate with one another over a high-speedinternal network such as an InfiniBand network. The C-modules, D-modulesand R-modules coordinate with one another to accomplish various IOprocessing tasks.

The write requests from the host devices identify particular data pagesto be written in the content addressable storage system 105 by theircorresponding logical addresses each comprising a LUN ID and an offset.

As noted above, a given one of the content-based signaturesillustratively comprises a hash digest of the corresponding data page,with the hash digest being generated by applying a hash function to thecontent of that data page. The hash digest may be uniquely representedwithin a given storage resource boundary by a corresponding hash handle.

The content addressable storage system 105 utilizes a two-level mappingprocess to map logical block addresses to physical block addresses. Thefirst level of mapping uses an address-to-hash (“A2H”) table and thesecond level of mapping uses a hash metadata (“HMD”) table, with the A2Hand HMD tables corresponding to respective logical and physical layersof the content-based signature mapping within the content addressablestorage system 105.

The first level of mapping using the A2H table associates logicaladdresses of respective data pages with respective content-basedsignatures of those data pages. This is also referred to logical layermapping.

The second level of mapping using the HMD table associates respectiveones of the content-based signatures with respective physical storagelocations in one or more of the storage devices 106. This is alsoreferred to as physical layer mapping.

For a given write request, both of the corresponding HMD and A2H tablesare updated in conjunction with the processing of that write request.

The A2H and HMD tables described above are examples of what are moregenerally referred to herein as “mapping tables” of respective first andsecond distinct types. Other types and arrangements of mapping tables orother content-based signature mapping information may be used in otherembodiments.

The logical block addresses or LBAs of a logical layer of the contentaddressable storage system 105 correspond to respective physical blocksof a physical layer of the content addressable storage system 105. Theuser data pages of the logical layer are organized by LBA and havereference via respective content-based signatures to particular physicalblocks of the physical layer.

Each of the physical blocks has an associated reference count that ismaintained within the content addressable storage system 105. Thereference count for a given physical block indicates the number oflogical blocks that point to that same physical block.

In releasing logical address space in the storage system, adereferencing operation is generally executed for each of the LBAs beingreleased. More particularly, the reference count of the correspondingphysical block is decremented. A reference count of zero indicates thatthere are no longer any logical blocks that reference the correspondingphysical block, and so that physical block can be released.

It should also be understood that the particular arrangement of storagecontroller processing modules 108C, 108D, 108R and 108M as shown in theFIG. 1 embodiment is presented by way of example only. Numerousalternative arrangements of processing modules of a distributed storagecontroller may be used to implement count-key-data track storagefunctionality in a clustered storage system in other embodiments.

Additional examples of content addressable storage functionalityimplemented in some embodiments by control modules 108C, data modules108D, routing modules 108R and management module(s) 108M of distributedstorage controller 108 can be found in U.S. Pat. No. 9,104,326, entitled“Scalable Block Data Storage Using Content Addressing,” which isincorporated by reference herein. Alternative arrangements of these andother storage node processing modules of a distributed storagecontroller in a content addressable storage system can be used in otherembodiments.

As indicated previously, the host devices 102 and content addressablestorage system 105 in the FIG. 1 embodiment are assumed to beimplemented using at least one processing platform each comprising oneor more processing devices each having a processor coupled to a memory.Such processing devices can illustratively include particulararrangements of compute, storage and network resources.

The host devices 102 and the content addressable storage system 105 maybe implemented on respective distinct processing platforms, althoughnumerous other arrangements are possible. For example, in someembodiments at least portions of the host devices 102 and the contentaddressable storage system 105 are implemented on the same processingplatform. The content addressable storage system 105 can therefore beimplemented at least in part within at least one processing platformthat implements at least one of the host devices 102.

The term “processing platform” as used herein is intended to be broadlyconstrued so as to encompass, by way of illustration and withoutlimitation, multiple sets of processing devices and associated storagesystems that are configured to communicate over one or more networks.For example, distributed implementations of the system 100 are possible,in which certain components of the system reside in one data center in afirst geographic location while other components of the system reside inone or more other data centers in one or more other geographic locationsthat are potentially remote from the first geographic location. Thus, itis possible in some implementations of the system 100 for the hostdevices 102 and the content addressable storage system 105 to reside indifferent data centers. Numerous other distributed implementations ofthe host devices 102 and/or the content addressable storage system 105are possible. Accordingly, the content addressable storage system 105can also be implemented in a distributed manner across multiple datacenters.

Additional examples of processing platforms utilized to implement hostdevices and/or storage systems in illustrative embodiments will bedescribed in more detail below in conjunction with FIGS. 6 and 7.

It is to be appreciated that these and other features of illustrativeembodiments are presented by way of example only, and should not beconstrued as limiting in any way.

Accordingly, different numbers, types and arrangements of systemcomponents such as host devices 102, network 104, content addressablestorage system 105, storage devices 106, storage controllers 108 andstorage nodes 115 can be used in other embodiments.

It should be understood that the particular sets of modules and othercomponents implemented in the system 100 as illustrated in FIG. 1 arepresented by way of example only. In other embodiments, only subsets ofthese components, or additional or alternative sets of components, maybe used, and such components may exhibit alternative functionality andconfigurations.

For example, in some embodiments, at least portions of the functionalityfor efficient storage of count-key-data tracks as disclosed herein canbe implemented in a host device, in a storage system, or partially in ahost device and partially in a storage system.

Accordingly, illustrative embodiments are not limited to arrangements inwhich all such functionality is implemented in a host device or astorage system, and therefore encompass various hybrid arrangements inwhich the functionality is distributed over one or more host devices andone or more storage systems, each comprising one or more processingdevices.

The operation of the information processing system 100 will now bedescribed in further detail with reference to the flow diagram of FIG.2, and with supporting reference to additional diagrams in FIGS. 3, 4and 5. The flow diagram of FIG. 2 illustrates a process for efficientstorage of count-key-data tracks in a content addressable storagesystem. The process includes steps 200 through 206, and is suitable foruse in system 100 but is more generally applicable to other types ofsystems in which it is desirable to store count-key-data tracks in anefficient manner that can take full advantage of any deduplicationand/or compression functionality available within that system. The stepsof the flow diagram are illustratively performed at least in part underthe control of a storage controller of a storage system, such as thedistributed storage controller 108 of content addressable storage system105. FIGS. 3, 4 and 5 show aspects of one possible implementation of theFIG. 2 process.

In step 200, a plurality of data records in a count-key-data format arereceived. For example, the data records in the count-key-data format maybe received in a storage system from one or more host devices. Asanother example, the data records in the count-key-data format may bereceived in one storage system from another storage system, such as in acontent addressable storage system from a mainframe storage system,possibly via one or more intermediate host devices. Different ones ofthe data records in the count-key-data format may be received fromdifferent sources of such data records, including different hostdevices, storage systems or other system entities.

An example of a given track 300 of data records in a count-key-dataformat in an illustrative embodiment is shown in FIG. 3. In thisexample, the given track 300 is also denoted as track i and comprises aplurality of data records, each having a count field, a key field and auser data field. There are r data records in track i in this example.The first data record has a count field containing a count value denotedCount 1, the second data record has a count field containing a countvalue denoted Count 2, and the r-th data record has a count fieldcontaining a count value denoted Count r. Similarly, the first datarecord has a key field containing a key value denoted Key 1, the seconddata record has a key field containing a key value denoted Key 2, andthe r-th data record has a key field containing a key value denoted Keyr. Each of the data records also includes a user data field which may bea variable length field. Although for simplicity of illustration theuser data fields are shown in the figure as having the same length, itshould be understood that the user data fields are more generallyvariable length fields.

For example, in some embodiments, a given track may comprise 56.5 KB ofdata records in count-key-data format, with each data record havingcount, key and data fields. The count and key fields are typicallysmall, in some cases on the order of 8 bytes, while the user data fieldis of variable length.

The count and key fields are an example of what are more generallyreferred to herein as count and key portions of the data records of thetrack 300. The count field of a given one of the data records in thisembodiment indicates the length of the given data record, and the keyfield includes key information of that data record. The key informationis illustratively utilized for various data management functions. Theuser data field of the given data record is an example of what is moregenerally referred to herein as a “remaining portion” of the given datarecord. Other types of count and key portions, remaining portions, andcount-key-data formats may be used in other embodiments. A given“remaining portion” as that term is broadly used herein may but need notcomprise all portions of a data record other than the count and keyportions.

In step 202, count and key portions of the received data records areseparated from remaining portions of the data records. The remainingportions of the data records generally include user data portions ofthose data records.

In step 204, the count and key portions of the data records are storedin at least one designated page of a set of pages of a logical storagevolume of a storage system.

In step 206, the remaining portions of the data records are stored inone or more other pages of the set of pages of the logical storagevolume of the storage system.

For example, in some implementations of steps 204 and 206, thedesignated page of the set of pages of the logical storage volumecomprises a first page of the set of pages and the one or more otherpages of the set of pages comprise respective ones of a sequence ofconsecutive pages following the first page.

The designated page illustratively comprises a plurality of entries forcount and key portions of respective ones of the data records with eachof the entries of the designated page comprising count and key portionsfor a given one of the data records and a pointer to a location of theremaining portion of the given one of the records in the one or moreother pages of the set of pages. The pointers illustratively compriserespective offsets indicating the locations of the respective remainingportions in the one or more other pages of the set of pages. Forexample, a given entry corresponding to a given data recordillustratively comprises a count value from a count field of the datarecord, a key value from a key field of the given data record, and anoffset denoting the location of the user data from the user data fieldof the given data record in the one or more other pages of the set ofpages.

FIG. 4 shows an example of a manner in which the data records of FIG. 3are stored utilizing a designated page for count and key portions andadditional pages for remaining portions in an illustrative embodiment.More particularly, in this example, track i of FIG. 3 is stored in a setof LUN pages 400 denoted Page 1, Page 2, . . . Page s. Page 1 is the“designated page” that stores the count and key portions of the datarecords of track i and respective corresponding pointers in thisexample, and Page 2 through Page s are the “other pages” that store theremaining portions of the data records of track i.

FIG. 5 shows a LUN page 500 that provides a more detailed view of Page 1of FIG. 4 containing count and key portions of the data records inassociation with respective pointers to remaining user data portions ofthose data records in an illustrative embodiment. More particularly, theLUN page 500 comprises the count and key portions of all of the datarecords of track i and respective corresponding pointers. The LUN page500 as shown comprises a plurality of entries for count and key portionsof respective ones of the data records with each of the entries of theLUN page 500 comprising count and key portions for a given one of thedata records and a pointer to a location of the remaining portion of thegiven one of the records in Page 2 through Page s in the set of LUNpages 400. The first entry of LUN page 500 has a count field containingCount 1, a key field containing Key 1, and a pointer to user data forData Record 1 of track i in Page 2 through Page s. Similarly, the secondentry of LUN page 500 has a count field containing Count 2, a key fieldcontaining Key 2, and a pointer to user data for Data Record 2 of tracki in Page 2 through Page s, and the r-th entry of LUN page 500 has acount field containing Count r, a key field containing Key r, and apointer to user data for Data Record r of track i in Page 2 through Pages.

As mentioned previously, the pointers in LUN page 500 in someembodiments more particularly comprise respective offsets indicating thelocations of the user data of the respective data records in Page 2through Page s. In such an arrangement, an offset value in an offsetfield of the first entry of LUN page 500 would identify the particularlocation of the user data of Data Record 1 in Page 2 through Page s. Theother entries would include similar offset values for the other datarecords. Again, other types of tracks, data records, fields, portionsand pages can be used in other embodiments.

An arrangement of the type described in conjunction with FIGS. 3 through5 separates the count and key portions of the data records of a trackfrom the user data portions of those data records, stores the count andkey portions in a first page of a set of pages with pointers to the userdata portions in other pages of the set of pages. Such an arrangementprovides significant advantages in terms of facilitating performance ofeffective deduplication and/or compression operations on the user dataportions. This effective deduplication and/or compression would nototherwise be possible if the count and key portions were storedinterspersed with their corresponding user data portions as in theoriginal received track. In addition, the example arrangement of FIGS. 3through 5 allows the location of user data for any of the data recordsof the track to be determined by simply reading the first page of theset of pages used to store those data records.

The particular processing operations and other system functionalitydescribed above in conjunction with the flow diagram of FIG. 2 arepresented by way of illustrative example only, and should not beconstrued as limiting the scope of the disclosure in any way.Alternative embodiments can use other types of processing operations forefficient storage of count-key-data tracks in a content addressablestorage system. For example, the ordering of the process steps may bevaried in other embodiments, or certain steps may be performed at leastin part concurrently with one another rather than serially. Also, one ormore of the process steps may be repeated periodically, or multipleinstances of the process can be performed in parallel with one anotherin order to implement a plurality of different efficient count-key-datatrack storage processes for respective different datasets or fordifferent storage systems or portions thereof within a given informationprocessing system.

Functionality such as that described in conjunction with the flowdiagram of FIG. 2 can be implemented at least in part in the form of oneor more software programs stored in memory and executed by a processorof a processing device such as a computer or server. As will bedescribed below, a memory or other storage device having executableprogram code of one or more software programs embodied therein is anexample of what is more generally referred to herein as a“processor-readable storage medium.”

A storage controller such as distributed storage controller 108 that isconfigured to control performance of one or more steps of the process ofthe flow diagram of FIG. 2 in system 100 can be implemented as part ofwhat is more generally referred to herein as a processing platformcomprising one or more processing devices each comprising a processorcoupled to a memory. A given such processing device may correspond toone or more virtual machines or other types of virtualizationinfrastructure such as Docker containers or Linux containers (LXCs). Thehost devices 102 and content addressable storage system 105 of system100, as well as other system components, may be implemented at least inpart using processing devices of such processing platforms. For example,in the distributed storage controller 108, respective distributedmodules can be implemented in respective containers running onrespective ones of the processing devices of a processing platform.

Illustrative embodiments of storage systems with functionality forefficient storage of count-key-data tracks as disclosed herein canprovide a number of significant advantages relative to conventionalarrangements.

For example, some embodiments provide content addressable storagesystems that are configured for efficient storage of count-key-datatracks of the type commonly utilized in a mainframe storage system thatdoes not have content addressable storage functionality. Suchembodiments can provide a high level of storage efficiency throughdeduplication and compression even when storing count-key-data tracks.The storage efficiency of the content addressable storage system istherefore not degraded in any significant way when storing data intypical mainframe storage system formats.

These illustrative embodiments overcome disadvantages that mightotherwise occur if the data records of a given storage track weresequentially stored in one or more pages such that count and keyportions of the data records are interspersed with the user dataportions of the data records throughout all of the pages. For example,storage of the data records in such a manner would tend to substantiallyreduce the effectiveness of any deduplication or compression operationthat is applied to the stored data records.

Some embodiments can be configured to run entirely within a contentaddressable storage system or other type of storage system, without anyneed for modification of host devices. For example, in some embodiments,a content addressable storage system is configured to emulate amainframe storage system in presenting a storage interface supporting acount-key-data format to one or more host devices.

In one or more embodiments, functionality for efficient storage ofcount-key-data tracks can be implemented in a host device, in a storagesystem, or partially in a host device and partially in a storage system.

It is to be appreciated that the particular advantages described aboveand elsewhere herein are associated with particular illustrativeembodiments and need not be present in other embodiments. Also, theparticular types of information processing system features andfunctionality as illustrated in the drawings and described above areexemplary only, and numerous other arrangements may be used in otherembodiments.

Illustrative embodiments of processing platforms utilized to implementfunctionality for efficient storage of count-key-data tracks will now bedescribed in greater detail with reference to FIGS. 6 and 7. Althoughdescribed in the context of system 100, these platforms may also be usedto implement at least portions of other information processing systemsin other embodiments.

FIG. 6 shows an example processing platform comprising cloudinfrastructure 600. The cloud infrastructure 600 comprises a combinationof physical and virtual processing resources that may be utilized toimplement at least a portion of the information processing system 100.The cloud infrastructure 600 comprises multiple virtual machines (VMs)and/or container sets 602-1, 602-2, . . . 602-L implemented usingvirtualization infrastructure 604. The virtualization infrastructure 604runs on physical infrastructure 605, and illustratively comprises one ormore hypervisors and/or operating system level virtualizationinfrastructure. The operating system level virtualization infrastructureillustratively comprises kernel control groups of a Linux operatingsystem or other type of operating system.

The cloud infrastructure 600 further comprises sets of applications610-1, 610-2, . . . 610-L running on respective ones of theVMs/container sets 602-1, 602-2, . . . 602-L under the control of thevirtualization infrastructure 604. The VMs/container sets 602 maycomprise respective VMs, respective sets of one or more containers, orrespective sets of one or more containers running in VMs.

In some implementations of the FIG. 6 embodiment, the VMs/container sets602 comprise respective VMs implemented using virtualizationinfrastructure 604 that comprises at least one hypervisor. Suchimplementations can provide storage functionality of the type describedabove for one or more processes running on a given one of the VMs.

An example of a hypervisor platform that may be used to implement ahypervisor within the virtualization infrastructure 604 is the VMware®vSphere® which may have an associated virtual infrastructure managementsystem such as the VMware® vCenter™. The underlying physical machinesmay comprise one or more distributed processing platforms that includeone or more storage systems.

In other implementations of the FIG. 6 embodiment, the VMs/containersets 602 comprise respective containers implemented using virtualizationinfrastructure 604 that provides operating system level virtualizationfunctionality, such as support for Docker containers running on baremetal hosts, or Docker containers running on VMs. The containers areillustratively implemented using respective kernel control groups of theoperating system. Such implementations can provide storage functionalityof the type described above for one or more processes running ondifferent ones of the containers. For example, a container host devicesupporting multiple containers of one or more container sets canimplement one or more instances of the FIG. 2 process for efficientstorage of count-key-data tracks.

As is apparent from the above, one or more of the processing modules orother components of system 100 may each run on a computer, server,storage device or other processing platform element. A given suchelement may be viewed as an example of what is more generally referredto herein as a “processing device.” The cloud infrastructure 600 shownin FIG. 6 may represent at least a portion of one processing platform.Another example of such a processing platform is processing platform 700shown in FIG. 7.

The processing platform 700 in this embodiment comprises a portion ofsystem 100 and includes a plurality of processing devices, denoted702-1, 702-2, 702-3, . . . 702-K, which communicate with one anotherover a network 704.

The network 704 may comprise any type of network, including by way ofexample a global computer network such as the Internet, a WAN, a LAN, asatellite network, a telephone or cable network, a cellular network, awireless network such as a WiFi or WiMAX network, or various portions orcombinations of these and other types of networks.

The processing device 702-1 in the processing platform 700 comprises aprocessor 710 coupled to a memory 712.

The processor 710 may comprise a microprocessor, a microcontroller, anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other type of processing circuitry, as well asportions or combinations of such circuitry elements.

The memory 712 may comprise random access memory (RAM), read-only memory(ROM), flash memory or other types of memory, in any combination. Thememory 712 and other memories disclosed herein should be viewed asillustrative examples of what are more generally referred to as“processor-readable storage media” storing executable program code ofone or more software programs.

Articles of manufacture comprising such processor-readable storage mediaare considered illustrative embodiments. A given such article ofmanufacture may comprise, for example, a storage array, a storage diskor an integrated circuit containing RAM, ROM, flash memory or otherelectronic memory, or any of a wide variety of other types of computerprogram products. The term “article of manufacture” as used hereinshould be understood to exclude transitory, propagating signals.Numerous other types of computer program products comprisingprocessor-readable storage media can be used.

Also included in the processing device 702-1 is network interfacecircuitry 714, which is used to interface the processing device with thenetwork 704 and other system components, and may comprise conventionaltransceivers.

The other processing devices 702 of the processing platform 700 areassumed to be configured in a manner similar to that shown forprocessing device 702-1 in the figure.

Again, the particular processing platform 700 shown in the figure ispresented by way of example only, and system 100 may include additionalor alternative processing platforms, as well as numerous distinctprocessing platforms in any combination, with each such platformcomprising one or more computers, servers, storage devices or otherprocessing devices.

For example, other processing platforms used to implement illustrativeembodiments can comprise converged infrastructure such as VxRail™,VxRack™, VxRack™ FLEX, VxBlock™ or Vblock® converged infrastructure fromVCE, the Virtual Computing Environment Company, now the ConvergedPlatform and Solutions Division of Dell EMC.

It should therefore be understood that in other embodiments differentarrangements of additional or alternative elements may be used. At leasta subset of these elements may be collectively implemented on a commonprocessing platform, or each such element may be implemented on aseparate processing platform.

As indicated previously, components of an information processing systemas disclosed herein can be implemented at least in part in the form ofone or more software programs stored in memory and executed by aprocessor of a processing device. For example, at least portions of thecount-key-data track storage functionality of one or more components ofa host device or storage system as disclosed herein are illustrativelyimplemented in the form of software running on one or more processingdevices.

It should again be emphasized that the above-described embodiments arepresented for purposes of illustration only. Many variations and otheralternative embodiments may be used. For example, the disclosedtechniques are applicable to a wide variety of other types ofinformation processing systems, host devices, storage systems, storagenodes, storage devices, storage controllers, count-key-data trackstorage processes and associated control logic. Also, the particularconfigurations of system and device elements and associated processingoperations illustratively shown in the drawings can be varied in otherembodiments. Moreover, the various assumptions made above in the courseof describing the illustrative embodiments should also be viewed asexemplary rather than as requirements or limitations of the disclosure.Numerous other alternative embodiments within the scope of the appendedclaims will be readily apparent to those skilled in the art.

What is claimed is:
 1. An apparatus comprising: a storage systemcomprising a plurality of storage devices and a storage controller; thestorage controller comprising a processor coupled to a memory; thestorage system being configured by the storage controller: to receive aplurality of data records in a count-key-data format; to separate countand key portions of the data records from remaining portions of the datarecords; to store the count and key portions of the data records in onedesignated page of a set of pages of a logical storage volume of thestorage system; and to store the remaining portions of the data recordsin one or more other pages of the set of pages of the logical storagevolume of the storage system.
 2. The apparatus of claim 1 wherein thedesignated page of the set of pages of the logical storage volumecomprises a first page of the set of pages.
 3. The apparatus of claim 2wherein the one or more other pages of the set of pages compriserespective ones of a sequence of consecutive pages following the firstpage.
 4. The apparatus of claim 1 wherein the data records are part of aparticular track comprising multiple data records in the count-key-dataformat.
 5. The apparatus of claim 1 wherein storing the count and keyportions of the data records in one designated page of a set of pages ofa logical storage volume of the storage system comprises storing thecount and key portions for a given one of the records in the designatedpage in association with a pointer to a location of the remainingportion of the given one of the records in the one or more other pagesof the set of pages.
 6. The apparatus of claim 1 wherein the designatedpage comprises a plurality of entries for count and key portions ofrespective ones of the data records with each of the entries of thedesignated page comprising count and key portions for a given one of thedata records and a pointer to a location of the remaining portion of thegiven one of the records in the one or more other pages of the set ofpages.
 7. The apparatus of claim 1 wherein the count portion for a givenone of the data records comprises a count field indicating a length ofthe given data record.
 8. The apparatus of claim 1 wherein the keyportion for a given one of the data records comprises a key fieldincluding key information of the given data record.
 9. The apparatus ofclaim 1 wherein the remaining portion for a given one of the datarecords comprises user data of the given data record.
 10. The apparatusof claim 1 wherein the storage system is configured to perform adeduplication operation on the one or more other pages of the set ofpages of the logical storage volume but not on the designated page ofthe set of pages.
 11. The apparatus of claim 1 wherein the storagesystem is configured to perform a compression operation on the one ormore other pages of the set of pages of the logical storage volume butnot on the designated page of the set of pages.
 12. The apparatus ofclaim 1 wherein the storage system comprises a content addressablestorage system.
 13. The apparatus of claim 1 wherein the storage devicescomprise respective non-volatile memory devices.
 14. The apparatus ofclaim 1 wherein the storage system comprises a clustered storage systemhaving a plurality of storage nodes each comprising a plurality ofstorage devices and wherein the storage controller is implemented in adistributed manner so as to comprise a plurality of distributed storagecontroller components implemented on respective ones of the storagenodes of the clustered storage system.
 15. A method comprising:receiving a plurality of data records in a count-key-data format;separating count and key portions of the data records from remainingportions of the data records; storing the count and key portions of thedata records in one designated page of a set of pages of a logicalstorage volume of a storage system; and storing the remaining portionsof the data records in one or more other pages of the set of pages ofthe logical storage volume of the storage system; wherein the method isperformed by at least one processing device comprising a processorcoupled to a memory.
 16. The method of claim 15 wherein the designatedpage of the set of pages of the logical storage volume comprises a firstpage of the set of pages and wherein the one or more other pages of theset of pages comprise respective ones of a sequence of consecutive pagesfollowing the first page.
 17. The method of claim 15 wherein thedesignated page comprises a plurality of entries for count and keyportions of respective ones of the data records with each of the entriesof the designated page comprising count and key portions for a given oneof the data records and a pointer to a location of the remaining portionof the given one of the records in the one or more other pages of theset of pages.
 18. A computer program product comprising a non-transitoryprocessor-readable storage medium having stored therein program code ofone or more software programs, wherein the program code when executed byat least one processing device causes said at least one processingdevice: to receive a plurality of data records in a count-key-dataformat; to separate count and key portions of the data records fromremaining portions of the data records; to store the count and keyportions of the data records in one designated page of a set of pages ofa logical storage volume of a storage system; and to store the remainingportions of the data records in one or more other pages of the set ofpages of the logical storage volume of the storage system.
 19. Thecomputer program product of claim 18 wherein the designated page of theset of pages of the logical storage volume comprises a first page of theset of pages and wherein the one or more other pages of the set of pagescomprise respective ones of a sequence of consecutive pages followingthe first page.
 20. The computer program product of claim 18 wherein thedesignated page comprises a plurality of entries for count and keyportions of respective ones of the data records with each of the entriesof the designated page comprising count and key portions for a given oneof the data records and a pointer to a location of the remaining portionof the given one of the records in the one or more other pages of theset of pages.